Deck 31: Protostome Animals

Question 1

Which of the following would not be found in a protostome with an incomplete digestive tract (blind gut)?

A) Central nervous system
B) Body cavity
C) Ectoderm
D) Endoderm
E) Anterior brain

Answer 1

B

Question 2

Which of the following animals have a hemocoel?

A) Bryozoans
B) Arthropods
C) Rotifers
D) Annelids
E) Nematodes

Answer 2

B

Question 3

Many lineages of lophotrochozoans have a type of free-living larva known as a

A) polyp.
B) planula.
C) trochophore.
D) nauplius.
E) medusa.

Answer 3

C

Question 4

Refer to the figure showing an arthropod exoskeleton. Which structure(s) would have allowed aquatic arthropods to invade terrestrial environments?

A) Ventral nerve cord
B) Longitudinal muscles
C) Hemocoel
D) Heart
E) Exoskeleton

Question 5

A wormlike body form enables animals to

A) escape predators.
B) exchange gases efficiently.
C) blend into their environments.
D) burrow efficiently through marine sediment or soil.
E) reproduce asexually.

Question 6

Spiral cleavage is found in a subset of lophotrochozoans, including the ribbon worms, annelids, and

A) phoronids.
B) mollusks.
C) bryozoans.
D) rotifers.
E) arrow worms.

Question 7

The evolution of a chitinous exoskeleton affected many aspects of arthropod evolution.The aspect that was least affected was the

A) division of labor among the body parts.
B) mode of locomotion.
C) pattern of growth.
D) system of gas exchange.
E) mode of digestion.

Question 8

Which statement about flatworms is false?

A) Some are parasitic.
B) They possess a mouth but no anus.
C) They are diploblastic.
D) They possess some degree of cephalization.
E) Some possess complex life cycles.

Question 9

Which feature of rotifers is also present in the flatworms, their sister group?

A) Complete gut
B) Pseudocoel
C) Gonads
D) Hemocoel
E) Digestive gland

Question 10

Refer to the figure. The organism depicted is a _______, which lacks specialized organs for _______.

A) rotifer; movement
B) nematode; reproduction
C) flatworm; gas exchange
D) flatworm; reproduction
E) bryozoan; gas exchange

Question 11

Which of the following is not one of the traits that unites the protostomes?

A) Dorsal nervous system
B) Anterior brain
C) Bilaterally symmetrical body plan
D) Development of a mouth from a blastopore (in many species)
E) All of the above are traits that unite the protostomes.

Question 12

The figure shows several bryozoans. Which statement about these organisms cannot be inferred from the evidence in the figure?

A) They are colonial.
B) They possess a lophophore.
C) They may have an external skeleton.
D) They are likely filter-feeders.
E) They have a trochophore larva.

Question 13

Which group is most likely to share a common lophotrochozoan ancestor with the annelids?

A) Nematodes
B) Mollusks
C) Vertebrates
D) Insects
E) Tardigrades

Question 14

Which of the following animals is least likely to possess an anus? (Consider whether or not the digestive tract is complete.)

A) Flatworms
B) Phoronids
C) Arrow worms
D) Annelids
E) Nematodes

Question 15

The entomologist Terry Erwin estimated that there were 30 million species of insects based on studies he conducted of beetles that fell from 19 trees treated with insecticide.Later studies, however showed that his estimate was probably too high.Which statement about the Erwin study is false?

A) It made assumptions about the number of species of host trees.
B) It made assumptions about the proportion of beetles that specialize on a specific tree species.
C) It made assumptions about the relative proportion of beetles to other insect groups.
D) It included chelicerates (spiders and mites), which was the reason for the overestimation.
E) It involved the collection of many previously undescribed beetle species.

Question 16

Animals with thin cuticles are generally restricted to moist habitats because

A) a thin cuticle allows water to be lost across the body surface.
B) there are fewer predators in these types of habitats.
C) these animals rely on flowing water to bring them food.
D) an animal moving through a moist habitat encounters less friction.
E) moist habitats increase efficiency of the lophophore.

Question 17

Periodic molting of the insect exoskeleton is necessary because

A) the growth of the exoskeleton is not sufficient to accommodate the body growing inside it.
B) an insect must consume large amounts of food to support the growth of the exoskeleton.
C) it prevents an insect from moving rapidly.
D) it attracts predators.
E) it accumulates toxins.

Question 18

For terrestrial arthropods, the advantage of a chitinous exoskeleton is that it

A) prevents the animal from dehydrating.
B) increases surface area for gas exchange.
C) increases the speed of movement.
D) provides a stored food supply.
E) increases the flexibility of movement.

Question 19

Refer to the figure showing an arthropod exoskeleton. Which structure is/are common to arthropods and annelids?

A) Ventral nerve cord
B) Muscles within appendage
C) Hemocoel
D) Exoskeleton
E) Muscles that move appendages

Question 20

Which of the following does not represent a correct pairing of a protostome group with one of its characteristics?

A) Bryzoans: coelomate
B) Annelids: complete digestive tract
C) Flatworms: complete digestive tract
D) Rotifers: no circulatory system
E) Nematodes: pseudocoelomate

Question 21

Which statement about rotifers is false?

A) They are acoelomates.
B) Their body cavity functions as a hydrostatic skeleton.
C) They locomote through the water by means of beating cilia.
D) Most species are smaller than some ciliate protists.
E) They have specialized internal organs.

Question 22

Unlike in all other living mollusks, in _______ the gas exchange organs, muscles, and excretory pores are repeated over the length of the body.These organisms were the most abundant mollusks during the Cambrian period, 500 million years ago, but only a few species survive today.

A) chitons
B) cephalopods
C) bivalves
D) gastropods
E) monoplacophorans

Question 23

Many flatworm species are parasitic.Which of the following is an adaptation of flatworms that is associated with a parasitic lifestyle?

A) A highly developed digestive system
B) A highly branched gastrovascular cavity
C) An organ system for oxygen transport
D) Absorption of nutrients through the body surface
E) Multiple pairs of appendages

Question 24

Which of the following is not associated with a parasitic lifestyle, as seen in tapeworms and flukes?

A) Complex digestive systems
B) Flattened body
C) Life cycles with several larval stages
D) Life cycles with multiple hosts
E) Reduced gastrovascular cavity

Question 25

In what way do brachiopods differ from bivalves?

A) Brachiopods release gametes into the water; bivalves have internal fertilization.
B) Brachiopods are terrestrial; bivalves are marine.
C) Brachiopod have a dorsoventral shell, while bivalve shells are lateral.
D) Brachiopods have a lophophore; bivalves do not.
E) Brachiopods move by means of a muscular foot; bivalves move by means of arms.

Question 26

You discover a new organism with the following characteristics: the body is wormlike and has a fluid-filled cavity, the long protrusible feeding organ looks like a proboscis, and a complete digestive tract is present.The organism is probably a(n)

A) arrow worm.
B) flatworm.
C) nematode.
D) ribbon worm.
E) horsehair worm.

Question 27

The molluscan body plan includes three unique, shared, derived characteristics that support the monophyly of the group: the _______, the _______, and the _______.

A) foot; radula; mantle
B) foot; mantle; shell
C) visceral mass; radula; mantle
D) visceral mass; mantle; shell
E) foot; visceral mass; mantle

Question 28

_______have open circulatory systems, a complete digestive tract, and a reduction of the coelom.

A) Rotifers
B) Annelids
C) Mollusks
D) Nematodes
E) Flatworms

Question 29

The term "rotifer," shares a root with the word "rotate," and refers to

A) the whirring motion of the cilia of the rotifer feeding apparatus.
B) the way rotifers spin in place on an attachment to the substrate.
C) the rotating motion of rotifers as they locomote through water.
D) the radial symmetry of rotifers.
E) the motion of food through the rotifer digestive tract.

Question 30

A segmented coelom is characteristic of

A) bryozoans.
B) mollusks.
C) annelids.
D) flatworms.
E) nematodes.

Question 31

Which of the following organisms are hermaphroditic (individuals possess both male and female reproductive structures)?

A) Phoronids
B) Oligochaetes
C) Squids
D) Rotifers
E) Chitons

Question 32

The large and remarkable pogonophoran annelids live near deep ocean hydrothermal (volcanic) vents where food items are scarce.How do pogonophorans, which have completely lost their digestive tracts, obtain most of their nutrition?

A) They are able to conduct photosynthesis.
B) Their tissues harbor endosymbiotic bacteria that fix carbon by oxidizing hydrogen sulfide and methane.
C) They fix carbon from minerals found in mud on the ocean floor.
D) They filter algae from ocean water.
E) They feed on fish that become entangled in their tentacles.

Question 33

Refer to the figure. Gas exchange in this animal occurs through

A) spiracles.
B) a thin, permeable body wall.
C) gills.
D) lungs.
E) a lophophore.

Question 34

Which statement about oligochaetes is false?

A) They are hermaphroditic.
B) They have separate nerve centers called ganglia.
C) They have a segmented coelom.
D) They have serially repeated organs.
E) Their zygotes undergo radial cleavage.

Question 35

In a mollusk, the _______ secretes the shell?

A) mantle
B) foot
C) visceral mass
D) radula
E) siphon

Question 36

Which group includes a segmented marine animal that is wormlike, has parapodia, and develops through spiral cleavage?

A) Nematodes
B) Annelids
C) Brachiopods
D) Mollusks
E) Flatworms

Question 37

Which statement about features of the phoronids is false?

A) There are fewer than 100 species.
B) They are active predators.
C) They secrete chitinous tubes.
D) They possess a lophophore.
E) There are relatively small, ranging in length from 5 to 25 cm.

Question 38

Some mollusks have a rasping feeding structure known as the

A) proboscis.
B) rhynchocoel.
C) corona.
D) radula.
E) mastax.

Question 39

Which of the following are not members of the annelid group?

A) Bryozoans
B) Polychaetes
C) Oligochaetes
D) Clitellates
E) Leeches

Question 40

In free-living flatworms, which function does not occur by simple diffusion?

A) Respiration
B) Absorption of nutrients
C) Excretion
D) Distribution of nutrients within the body
E) Chemoreception

Question 41

Eight overlapping calcareous plates and a feeding structure called a radula occur in which lophotrochozoan group?

A) Slugs
B) Bivalves
C) Chitons
D) Gastropods
E) Monoplacophorans

Question 42

Nautiluses are unique among living cephalopods in that they have

A) an excurrent siphon.
B) eyes that are comparable to vertebrate eyes.
C) an incurrent siphon.
D) a chambered shell.
E) tentacles.

Question 43

Which ecdysozoan group contains fewer than 100 species?

A) Copepods
B) Priapulids
C) Arthropods
D) Insects
E) Nematodes

Question 44

The kinorhynchs and loriciferans are most closely related to

A) nematodes.
B) crustaceans.
C) tardigrades.
D) chelicerates.
E) priapulids.

Question 45

The possession of a relatively thin cuticle that is molted periodically as an animal grows to full size is a feature of

A) chelicerates.
B) myriapods.
C) hexapods and crustaceans.
D) tardigrades.
E) priapulids, kinorhynchs, and loriciferans.

Question 46

An animal that has a hemocoel, muscles attached to the inside of a rigid exoskeleton, and a complete digestive tract would most likely be a(n)

A) nematode.
B) annelid.
C) arthropod.
D) mollusk.
E) arrow worm.

Question 47

Nematodes are important in global ecosystems because

A) many nematodes are microscopic and contribute to substrate composition.
B) parasitic nematodes have multiple stages, affecting multiple species.
C) nematode numbers contribute a huge proportion to overall biomass.
D) scavenging nematodes contribute to nutrient cycling.
E) nematodes provide a nutrient base for other animals.

Question 48

Which statement about the mantle of mollusks is false?

A) It is present in all groups of mollusks except the octopuses.
B) In terrestrial gastropods, it is modified into a lung.
C) It is part of a filtering device used for feeding in bivalves.
D) It is the mechanism of jet propulsion in cephalopods.
E) It secretes the shell that provides external protection in most molluscan groups.

Question 49

Some cephalopods have a modified excurrent siphon and mantle to allow them to

A) ingest large prey.
B) alter their buoyancy.
C) move rapidly through the water.
D) attach to a substrate.
E) become parasitic.

Question 50

Caenorhabditis elegans is easy to cultivate, matures in 3 days, and has a fixed number of body cells.This explains why it

A) has been granted the epithet "elegans."
B) is a model organism for laboratory studies.
C) is a nematode.
D) is a soil-inhabiting species.
E) is considered an ancestral ecdysozoan.

Question 51

Functions of arthropod appendages include all of the following except

A) walking.
B) gas exchange.
C) grasping of food.
D) swimming.
E) defense.

Question 52

Flatworms differ from nematodes in that flatworms

A) are radially symmetrical, whereas nematodes are bilaterally symmetrical.
B) lack a cuticle, whereas nematodes secrete a cuticle that they molt.
C) have two embryonic cell layers, whereas nematodes have three.
D) have two openings to the digestive cavity, whereas some nematodes lack a digestive tract.
E) lack an anterior brain, whereas nematodes have a small anterior brain.

Question 53

Which statement about the contribution of arthropod characteristics to diversity is false?

A) Encasement of the body in a rigid exoskeleton provides support for walking in water or on land.
B) Stingers are used in defense.
C) Body segments are operated by individual muscles.
D) Specialization of appendages provides for different functions.
E) Muscles are attached within the exoskeleton.

Question 54

A thick cuticle in ecdysozoans

A) allows for greater gas exchange surface area.
B) serves as an exoskeleton.
C) is retained throughout the life of the animal.
D) stores metabolic waste products.
E) stores energy.

Question 55

Which structures are specializations of the molluscan foot?

A) Siphon, shell, and radula
B) Arms and burrowing foot
C) Tentacles and reproductive structures
D) Arms, tentacles, and mantle cavity
E) Siphon and shell

Question 56

Parasitic nematodes differ from free-living species in that parasitic nematodes

A) have simple life cycles.
B) have multiple stages in their life cycles within the same host.
C) cause elephantiasis in humans.
D) are mainly detritivores.
E) reproduce asexually.

Question 57

An animal with bilateral symmetry, a pseudocoelom, a tubular digestive system, and a multilayered cuticle is most likely a(n)

A) arrow worm.
B) nematode.
C) flatworm.
D) polychaete.
E) annelid.

Question 58

Which statement about locomotion in nematodes is true?

A) Rhythmically beating cilia propel the animal forward.
B) Circular and longitudinal muscles work against each other to move the animal forward.
C) Longitudinal muscles contract to move the animal forward.
D) A series of hairs that project backward engage the substrate; back-and-forth movements move the animal forward.
E) Water expelled through specialized ducts moves the animal forward.

Question 59

Which of the following has a pseudocoel?

A) Phoronids
B) Horsehair worms
C) Brachiopods
D) Chelicerates
E) Hexapods

Question 60

Trichinella spiralis, the causative agent of the disease trichinosis, is a

A) ribbon worm.
B) flatworm.
C) rotifer.
D) nematode.
E) annelid.

Question 61

The centipedes and millipedes belong to which group?

A) Hexapods
B) Arachnids
C) Myriapods
D) Annelids
E) Chelicerates

Question 62

A very small animal (about 0.5‒1.5 mm in length) with fleshy, unjointed legs that lives in marine sand is most likely a(n)

A) tardigrade.
B) onychophoran.
C) chelicerate.
D) crustacean.
E) hexapod.

Question 63

Insects differ from other hexapods in that most groups possess

A) paired wings.
B) three body regions: head, thorax, and abdomen.
C) a dorsal nerve cord.
D) six pairs of appendages.
E) an exoskeleton.

Question 64

Which of the following is a shared characteristic that has most clearly linked onychophorans to the arthropods?

A) Soft, fleshy legs
B) Soft, segmented bodies
C) Unjointed, claw-bearing legs
D) Molecular characteristics
E) Habitats of leaf litter in humid tropical environments

Question 65

In the evolution of insects, _______ allowed the exchange of gases with the air, leading to the exploitation of terrestrial environments.

A) tracheae
B) gills
C) lophophores
D) chelicerae
E) dorsal circulatory vessels

Question 66

Which of the following statements about spider webs and threads is false?

A) The webs can function as a home.
B) The threads are composed primarily of carbohydrates.
C) The threads are produced by modified abdominal appendages connected to internal secretory glands.
D) The webs function as a snare for catching prey.
E) The threads provide safety lines for climbing.

Question 67

Which of the following is not a characteristic of most insect species?

A) The ability to fly
B) Three basic body regions
C) A complex respiratory system, including lungs
D) Paired antennae
E) A digestive system

Question 68

_______ are so numerous that they are thought to be the most abundant of all marine arthropods.

A) Crustaceans
B) Millipedes
C) Nematodes
D) Barnacles
E) Insects

Question 69

In flatworms, the advantage a dorsoventrally flattened body is that it allows them to

A) hide from predators.
B) move quickly through the environment.
C) meet their gas exchange requirements without a transport system.
D) grow to very large sizes.
E) filter-feed.

Question 70

The _______ have bodies that are divided into two parts: a head region that bears two pairs of appendages modified to form mouthparts, and a trunk region that typically has four pairs of walking legs.

A) chelicerates
B) crustaceans
C) hexapods
D) nematodes
E) myriapods

Question 71

Fertilized eggs of most crustacean species

A) are laid in hollowed nests in the sand.
B) are attached to the outside of the female's body until hatching.
C) are spawned into the water column.
D) develop within a shell and then hatch as an instar larva.
E) go through development within a pupal case.

Question 72

Horseshoe crabs are called living fossils because they

A) live in holes in rocks.
B) are chelicerates, a primitive clade.
C) are morphologically similar to fossil horseshoe crabs from millions of years ago.
D) crawl into the intertidal zone in large numbers to mate and lay eggs.
E) scavenge and prey on bottom-dwelling animals.

Question 73

The wingless insects belong to which of the following groups?

A) Hexapods
B) Pterygotes
C) Myriapods
D) Arachnids
E) Chelicerates

Question 74

Which group contains the largest number of species?

A) Spiders
B) Crustaceans
C) Centipedes
D) Millipedes
E) Tardigrades

Question 75

Approximately what proportion of living species on Earth are insects?

A) 43 percent
B) 25 percent
C) 80 percent
D) 56 percent
E) 10 percent

Question 76

Which statement about tracheae in insects is false?

A) They are made up of are air sacs and tubular channels.
B) They penetrate virtually every part of an insect's body.
C) They extend from external openings inward, to tissues throughout the body.
D) They provide oxygen to an insect's tissues.
E) They extend through a single tube to an insect's mouth.

Question 77

The trilobite fossil record is very rich because

A) their reproductive rate was extremely high.
B) they were able to thrive both on land and in water.
C) their appendages had multiple functions.
D) they had heavy exoskeletons that readily fossilized.
E) they were the only arthropods with an unsegmented body.

Question 78

_______ are probably most similar to ancestral arthropods.

A) Chelicerates
B) Nematodes
C) Crustaceans
D) Onychophorans
E) Trilobites

Question 79

_______ can survive for at least 10 years in a dormant, dehydrated state.

A) Myriapods
B) Onychophorans
C) Pycnogonids
D) Tardigrades
E) Trilobites

Question 80

Which crustacean group bears a superficial resemblance to mollusks?

A) Isopods
B) Copepods
C) Barnacles
D) Decapods
E) Water fleas